1. Field of the Invention
This invention relates to air filters and more particularly to a filter assembly for use in dust collecting systems which utilizes a conical filter element mounted within a cylindrical filter element.
2. Description of the Related Art
In dust collecting systems, the air filters employed must be capable of filtering out fine particles of foreign matter such as dirt particles and dust to avoid their entry into the breathing space. Filters capable of filtering out fine particles offer considerable resistance to the flow of air. One way of alleviating this problem is to provide a large area filtering surface by successively bending a flat filtering media back and forth on itself to form a pleated or undulated configuration. Also, as described in U.S. Pat. No. 5,750,024 issued May 12, 1998 to Spearman, a conical filter element mounted within a cylindrical housing can be employed with the air to be cleaned fed into the base of the conical element with the filtered air being fed out from the space between the housing and the filter element. As the space between the conical element and the housing increases in the direction of flow, the velocity of the air flow tends to decrease which provides for more efficient filtering action.
The space occupied by a filter unit for a given amount of filtering action is often a critical factor. As noted above, the attainment of greater filtering action within a limited space can be achieved by pleating the filtering medium. The achievement of even greater filtering action within a given space is highly desirable.